Mobile app back-end development

Mobile app
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Introduction of new features to a web app, building back-end for a mobile app, Swagger doc development

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Creation of a new server compatible with the already built apps, additional services, and custom libraries.

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Tech stack

Next.js, Nest js, swagger.


One of the Europe’s leading hotel network based in Germany. The client unites eight different hotel brands in their business. The hotel geography includes 19 countries globally, where our client owns over 160 hotels.


Our client’s key challenge was to completely rework the server part of the existing product. It was essential to rebuild the product logic, improve and automate current processes with due regard to a fast scale-up and significant changes in the client’s business. A full-stack developer from Modsen joined the project. His tasks included:

  • timely creation of new endpoints
  • introduction of all necessary edits and corrections
  • error analysis at all testing stages, error correction
  • seamless transition from the old back-end to the new one
  • refactoring and optimization of the server app
  • making changes in email service (addition of new functions)
  • addition of new information and logic in the web application
  • product integration with Strapi and other external services
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Having assessed the scope of the app overhaul, we suggested how we could improve the project involving one experienced full-stack engineer.

As we planned to migrate the application from PHP to NodeJS and NestJS, we proceeded to a detailed review both of the back-end and front-end logic. We have completed the following:

  • Creation of a server-based app divided into separate modules
  • Development of Swagger doc (API documentation)
  • Integrations with external enterprise services
  • Report analysis on Sentry
  • Logic adjustment in React Native (mobile app) and creation of a new logic for seamless migration
  • Change and addition of logic in microservices (NestJS)
  • API extension and change of the service logic
Node JS app


The application overhaul was completed without stops within the approved timeframe. The client has already launched the full version of the new app, and it demonstrates great results. The key outcomes of the project are:

  • fast integration into the project, putting both the mobile and server-based apps into production successfully and within the time limits
  • display of additional information for users and more user-friendly check-in operation during the booking
  • improved convenient hotel registration via email, reduced time for booking, and increased number of bookings

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